1. Field of the Invention
Apparatuses consistent with the present invention relates to a multi-core optical fiber preferably applied to an imaging method using an optical fiber such as a confocal fluorescent imaging method.
2. Description of the Related Art
In many medical fields such as gastroenterology, pulmonary disease, or cardiovascular disease, endoscopes are employed for direct observation of surfaces of tissues or as auxiliary apparatuses for medicine. Further, fluorescence diagnostics carried out in combination with an endoscope attracts great deal of attention.
A tissue irradiated and excited by excitation light emits a fluorescent light having a characteristic spectrum. When the tissue has a lesion such as a tumor or a cancer, the tissue emits a particular fluorescent light having a spectrum different from the normal characteristic spectrum. The fluorescence diagnostics is a diagnostic method utilizing such a characteristic to discern a tissue having a lesion from a normal tissue. As this diagnostic method does not require collection of tissues from a patient's body, patients are released from physical burden. This is one of the many advantages of this method. Japanese Patent Application Laid-open No. H08-224240 discloses a related art.
A confocal fluorescent imaging method utilizing a multi-core optical fiber is often used in combination with the fluorescence diagnostics. In this method, a plurality of excitation light beams having different wavelengths irradiate a tissue through a multi-core optical fiber and then fluorescent lights with the excitation lights from the tissue are collected through the optical fiber. Separation of the fluorescent lights from the excitation lights produces fluorescent spectra. As cores embedded in the multi-core optical fiber have two-dimensional arrangement, such information processing carried out on the cores gives a two-dimensional image. Further, such processing reciprocally carried out with changing a vertical position and filtering information only from each focal point provides a confocal image. Published Japanese translation of International Application No. 2005-532883 discloses a related art.